Getting started

var myFirstAsyncApi = new AsyncApiDocument
{
  Info = new AsyncApiInfo
  {
    Title = "my first asyncapi"
  },
  Channels = new Dictionary<string, AsyncApiChannel>
  {
    {
	"users", new AsyncApiChannel
	{
	    Subscribe = new AsyncApiOperation
	    {
		OperationId = "users",
		Description = "my users channel"
	    }
	}
    }
  }
};
var yaml = myFirstAsyncApi.SerializeAsYaml();
//asyncapi: '2.6.0'
//  info:
//    title: my first asyncapi
//  channels:
//    users:
//      subscribe:
//        operationId: users
//        description: my users channel

Reading

var httpClient = new HttpClient
{
  BaseAddress = new Uri("https://raw.githubusercontent.com/asyncapi/spec/"),
};

var stream = await httpClient.GetStreamAsync("master/examples/streetlights-kafka.yml");
var asyncApiDocument = new AsyncApiStreamReader().Read(stream, out var diagnostic);